Scattered showers arrived too late

Scattered showers in the Southeast during the latter part of August may have been too little too late, as a portion of the parched region continues to be categorized as being in an exceptional drought.

Exceptional drought — the most severe of four drought levels — covered about 88,000 square miles, according to the U.S. Drought Monitor’s final August report. This included about 75 percent of Alabama, 43 percent of Tennessee, 40 percent of Georgia and 10 percent of North Carolina, as well as smaller portions of Florida and South Carolina.

Despite scattered rains of 4 inches or more, much of the Southeast remained hot and dry and crops and pastureland continued to deteriorate. Topsoil was rated dry to very dry for 92 percent or more of Alabama, Kentucky and Tennessee, 85 percent or more of the Carolinas and Arkansas, and 75 percent of Georgia.

As for crop conditions, 53 percent or more of the corn was rated poor to very poor in Tennessee and North Carolina, and cotton was 58 percent or more poor to very poor in Alabama and Tennessee.

Many streams in the Southeast were in the lower 25 percentile. In Georgia, drought conditions worsened dramatically from the beginning through the end of August, according to David Stooksbury, state climatologist and University of Georgia professor of engineering and atmospheric sciences.

“Widespread triple-digit high temperatures and very little rainfall have caused soil moisture levels to plummet, stream flows to approach record lows, and groundwater and lake levels to drop sharply,” said Stooksbury in late August.

Daily maximum temperatures did drop from the century mark after Aug. 24 across much of the Southeast, providing some respite from August’s persistent extreme heat. Numerous temperature records were expected to be broken when the final August numbers were tallied. Birmingham, Ala., for example, which endured 14 days with triple-digit heat in August, is likely to end up with the hottest month on record. Oak trees on ridges are reportedly dying in the state, and 30 percent of long-term stream gauges were at all-time lows.

Stooksbury says the only exception to Georgia’s worsening drought was the interior southeast portion of the state, where 30-day rainfall amounts were between 130 to 200 percent of normal.

In late August, of Georgia’s 159 counties, drought conditions were classified as exceptional in 70, extreme in 40, severe in 15, moderate in 13 and mild in six, with 11 counties classified as abnormally dry. Four counties were classified as not being in a drought.

Drought conditions are expected to be “exceptional” about once every 100 years, “extreme” once in 50 years and “severe” once in 20 years. The classifications are based on many indicators, including rainfall since Oct. 1 and over the past 180, 90, 30 and 14 days, soil moisture, stream flows, groundwater levels and reservoir levels.

“Most stream flows across west and north Georgia are at or near record-low flows for late August,” says Stooksbury. “The Chattooga River in the northeast mountains is approaching an all-time record flow, going back 67 years. In southwest Georgia, Spring Creek near Iron City has stopped flowing. Soil moisture loss to evaporation and plant use is now running between one-quarter and one-third inch per day, and groundwater levels remain low statewide for this time of year.”

And Stooksbury doesn’t see much relief in sight. “In August and September, our best hope for widespread drought relief is from tropical weather systems. Without these, we can expect the drought to worsen over the next two months,” he says.

Weather experts at the National Weather Service’s Climate Prediction Center agree with Stooksbury’s gloomy prediction. The center says there’s a good chance for below-normal rainfall or other precipitation for Alabama and other parts of the lower Southeast in November through January and in each three-month period starting with December, January, February and March.

If that happens, it’ll mean a continuation of the current drought. The center expects a La Nina event, signaled by cooler-than-normal surface water in the eastern Pacific Ocean near the equator, to start affecting weather in the United States by November.

Generally, when La Nina appears, the Southeast tends to receive less-than-normal rainfall, in part because high pressure diverts storms farther north.

“Despite some improvement likely later in the season, drought should largely persist from Kentucky into western Tennessee, and could even expand westward into Missouri and Arkansas,” according to a statement released by the center.